Download Dietary Reference Intakes: Implications for Fiber

Nutrition Science and Policy
January 2006: 31–38
Dietary Reference Intakes: Implications for Fiber Labeling
and Consumption: A Summary of the International Life
Sciences Institute North America Fiber Workshop, June 1-2,
2004, Washington, DC
Julie R. Jones, PhD, David M. Lineback, PhD, and Marci J. Levine, PhD
© 2006 International Life Sciences Institute
doi: 10.1301/nr.2006.jan.31–38
INTRODUCTION
Since the recognition of the importance of dietary
fiber for good nutrition, multiple definitions of the term
Dr. Jones is with the Department of Family, Consumer and Nutritional Sciences, College of St. Catherine, Minneapolis, Minnesota; Dr. Lineback is with the
Joint Institute for Food Safety & Applied Nutrition,
University of Maryland, College Park, Maryland; Dr.
Levine is with the North American Branch of the International Life Sciences Institute (ILSI NA), Washington,
DC; Drs. Jones and Lineback are scientific advisors
for the ILSI NA Technical Committee on Carbohydrates.
Please address all correspondence to: Dr. Marci
Levine, ILSI North America, One Thomas Circle NW,
Ninth Floor, Washington, DC 20005; Phone: 202-6590074; Fax: 202-659-3859; E-mail: [email protected].
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“fiber” have been developed. The Institute of Medicine
(IOM) recently defined dietary fiber1 at the request of the
US Food and Drug Administration (FDA). In response to
their definition, the North American branch of the International Life Sciences Institute (ILSI NA) Technical
Committee on Carbohydrates held a workshop entitled
“Dietary Reference Intakes: Implications for Fiber Labeling and Consumption,” June 1-2, 2004 in Washington, DC. Participants discussed the merits and limitations
of the IOM definition compared with other definitions. In
attendance were representatives from industry, academia, US and Canadian government agencies, and scientific associations.
HISTORY OF DEFINITIONS OF FIBER
The term “dietary fiber” was originally coined by
Hipsley in 1953.2 In 1972, Trowell et al.3 proposed a
definition of dietary fiber as “the skeletal remains of
plant cells that are resistant to digestion (hydrolysis) by
enzymes of man.” Between 1972 and 1976, a series of
hypotheses were advanced relating the consumption of
dietary fiber to various health states, including prevention of constipation, diverticular disease, hiatus hernia,
appendicitis, varicose veins, piles (hemorrhoids), diabetes, obesity, coronary heart disease, cancer of the large
bowel, and gallstones, with implications in duodenal
ulcers, breast cancer, and blood clotting. By 1976, it was
learned that other plant components not in the plant cell
wall, e.g., mucilages, gums, and pectins, were also resistant to digestion. Therefore, Trowell’s definition was
revised to “dietary fiber is the endogenous components
of the plant polysaccharides and lignin which are resistant to hydrolysis by digestive enzymes of man.”4 In the
late 1970s, international surveys showed that the 1976
Trowell definition was the proper basis for a working
definition of dietary fiber and related methods of determination (analysis).5,6
By 1981, the dietary fiber definitions proposed in the
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Multiple definitions of dietary fiber have been developed and are in use around the world. The definitions
vary as to which substances are considered to be
fibers, the analytical methods utilized to identify and
measure these fibers, and whether physiological criteria are part of the definition. A workshop entitled
“Dietary Reference Intakes: Implications for Fiber
Labeling and Consumption” was held by the International Life Sciences Institute North America Technical
Committee on Carbohydrates to review the fiber definitions recently published by the Institute of Medicine
(IOM) of the National Academies. Presentations and
facilitated discussions reviewed the rationale for the
IOM definitions of dietary fiber, functional fiber, and
total fiber in light of evolving nutritional science. Also
discussed were potential analytical, regulatory, and
consumer issues involved if the US Food and Drug
Administration and/or Health Canada were to implement the IOM’s recommendations. Issues, concerns,
and questions to be addressed are summarized here.
Dietary fiber is the edible parts of plants or analogous carbohydrates that are resistant to digestion
and absorption in the human small intestine with
complete or partial fermentation in the large intestine. Dietary fiber includes polysaccharides, oligosaccharides, lignin, and associated plant substances.
Dietary fibers promote beneficial physiological effects including laxation, and/or blood cholesterol
attenuation, and/or blood glucose attenuation.12
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This definition reflects the desire to describe fiber
chemically, structurally, and physiologically. It builds on
prior knowledge of scientific and regulatory efforts,
while allowing for the incorporation of potential future
discoveries.
At about the same time the AACC was developing a
definition for fiber, the IOM was developing new dietary
reference intakes (DRIs). As part of the DRI process, the
Panel on the Definition of Dietary Fiber was formed as
part of the DRI review of macronutrients to propose a
definition(s) for dietary fiber and provide a rationale for
its definition(s).1,13 Part of developing a definition involves studying existing definitions and identifying how
they differ from one another. The IOM panel expressed
the desire to move from the analytically based de facto
definition to one that recognizes numerous physiological
effects of fiber.13
The report13 from the IOM fiber panel discusses
which substances should be called dietary fiber, particularly since some animal sources (e.g., chitosan) could be
determined by current analytical methods to be dietary
fiber. Another issue was the physical state of the fiber, or
whether it should remain intact. Further, the report of the
IOM fiber panel discussed whether a dietary fiber needed
to exert a particular health benefit. It stated that, without
a formal definition, compounds that may have physiological fiber-like benefits but are not considered to be
dietary fiber by current AOAC methods of analysis could
not be called dietary fiber. In contrast, materials that are
determined to be dietary fiber by these methods but do
not have beneficial physiological effects can still be
called dietary fiber. The IOM panel recognized that
non-digestible carbohydrates are often isolated to concentrate a desirable fiber component or benefit of the
source material, and that this isolated fiber could be
added to products to enhance health benefits. Therefore,
the IOM fiber panel proposed that isolated fiber components should be considered separately and have proven
physiological benefits in humans, and proposed the following definitions:
● Dietary fiber consists of non-digestible carbohydrates
and lignin that are intrinsic and intact in plants.
● Added fiber consists of isolated, non-digestible carbohydrates that have beneficial physiological effects
in humans.
● Total fiber is the sum of dietary fiber and added
fiber.13
After receipt of comments on the IOM fiber panel’s
recommendations and further deliberations on the definitions, the DRI Panel on Macronutrients revised the
definition by changing “added” to “functional,” with the
following result:
● Dietary fiber consists of non-digestible carbohydrates
and lignin that are intrinsic and intact in plants.
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early 1970s evolved to the following: “dietary fiber
consists of the remnants of edible plant cells, polysaccharides, lignin, and associated substances resistant to
digestion (hydrolysis) by the alimentary enzymes of
humans.”7,8 This definition included cellulose, hemicelluloses, lignin, gums, modified celluloses, mucilages,
oligosaccharides, pectin, and associated minor substances such as waxes, cutin, and suberin.
In 1981, the Association of Official Analytical
Chemists (AOAC) held an international workshop at
which they reached consensus on this definition and
resolved to move toward practical applications. The
AOAC determined that methods of analyzing dietary
fiber should be rugged, able to simulate the human
digestive behavior designated in the definition, and that
competent laboratories should be able to analyze all
foods.6 The enzyme-gravimetric method called “Official
Method of Analysis 985.29”9 does capture most of the
substances that the working consensus definition7,8 prescribed as total dietary fiber.7 Other AOAC methods
have since been developed to analyze, for example,
insoluble dietary fiber (AOAC Method 991.42) and soluble dietary fiber (AOAC Method 993.19). However, an
interesting phenomenon occurred in which the most
widely used method for measuring dietary fiber, AOAC
Method 985.29, began to be used as the definition of
fiber itself by the FDA and by many other countries
worldwide.10 This is exemplified at the international
level by the 1995 Food and Agriculture Organization
(FAO)/World Health Organization (WHO) Codex Alimentarius Commission definition of dietary fiber: “dietary fiber is the edible plant or animal material not
hydrolyzed by the endogenous enzymes of the human
digestive tract as determined by the agreed upon method.”11 AOAC official methods of analysis for dietary
fiber have been adopted by many countries, including the
United States, as the basis for food and food product
labeling.10
Unfortunately, definitions based on analytical methods do not include reference to the physiological effects
of dietary fiber hypothesized years earlier. Therefore, the
American Association of Cereal Chemists (AACC) appointed an expert committee to evaluate the definitions
of dietary fiber and solicit worldwide input. The 2000
AACC definition is:
Functional fiber consists of isolated, non-digestible
carbohydrates that have beneficial physiological effects in humans.
● Total fiber is the sum of dietary fiber and functional
fiber.1
A proposal for a definition and methods of analysis
of dietary fiber content is also the subject of discussion
by the Codex Committee on Nutrition and Foods for
Special Dietary Uses.14 The definition under consideration states:
●
Dietary fibre consists either of Edible, naturally occurring in the food as consumed, non
digestible material composed of carbohydrate
polymers* with a degree of polymerisation
(DP) not lower than 3, or of
Synthetic carbohydrate polymers (DP ⱖ 3).
Dietary fibre is neither digested nor absorbed
in the small intestine and has at least one of the
following properties:
Increase stools bulk
Stimulate colonic fermentation**
Reduce blood total and/or LDL cholesterol
levels
Reduce post-prandial blood glucose and /or
insulin levels.
* When derived from a plant origin dietary
fibre may include fractions of lignin and/or
other compounds when associated with polysaccharides in the plant cell walls and if these
compounds are quantified by the AOAC gravimetric analytical method for dietary fiber
analysis: Fractions of lignin and the other compounds (Proteic fractions, phenolic compounds, waxes, saponins, phytates, cutin, phytosterols, etc.,) intimately “associated” with
plant polysaccharides are often extracted with
the polysaccharides in the AOAC 991.43
method. These substances are included in the
definition of fibre insofar as they are actually
associated with the poly-oligo-saccharidic
fraction of fibre. However, when extracted or
even re-introduced into a food containing non
digestible polysaccharides, they cannot be defined as dietary fibre. When combined with
polysaccharides, these associated substances
may provide additional beneficial effects.
** The statement “Stimulation of colonic fermentation” is added to take into account the
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TESTS AND CRITERIA FOR DISTINGUISHING
DIETARY AND FUNCTIONAL FIBERS
The IOM dietary fiber definition as finally developed1 includes plant cell wall and storage carbohydrates
common in foods, and includes natural and manufactured
or isolated and low-molecular-weight carbohydrates as
functional fiber. This definition allows for the inclusion
of isolated fibers for incorporation into foods and a
declaration as fiber once physiological effects in humans
are established. As with other macronutrients, investigations into the health effects of fiber consumption drive
research in two directions: analytical methods to detect
and measure fiber and clinical studies to establish physiological and health effects of fiber. The tests, criteria,
and issues surrounding these two areas were discussed at
the workshop.
Analytical Methods
Numerous methods exist to measure various components and combinations of fiber substances. Presently,
various AOAC-approved methods are based on the fact
that, physiologically, dietary fibers remain undigested by
human enzymes.7 These methods use combinations of
enzyme preparations, separations, and purifications to
isolate non-digestible fiber fractions, which are then
assayed by a number of validated procedures. However,
no method exists to distinguish between intrinsic fiber
and that which is intentionally introduced into a food
product. Also, the various methods do not necessarily
identify the same combinations of compounds as dietary
fiber. For example, AOAC Method 985.29 captures some
inulin in its determination of dietary fiber, while AOAC
Method 994.13 does not measure inulin. Several of these
methods were discussed at the workshop to explore their
strengths and weaknesses under the IOM definition.
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Carbohydrate polymers (DP ⱖ 3), which have
been obtained from food raw material by physical, enzymatic or chemical means, or of
effects resulting from the fermentation of fibre
(production of metabolites, modification of the
flora, effects associated with acidification of
the lumen contents, with modification of certain enzymatic activities (e.g. effect on glycuro-conjugated estrogens) or the production
of a large quantity of short chain fatty acids
and in particular butyrate which is thought to
contribute to the proper functioning of the
colonic mucosa and which might be beneficial
in the prevention of several types of colon
disease, including colon cancer. The physiological effects of fibre cannot be restricted to
the colon. Epidemiological and interventional
studies have demonstrated that protective
properties of fibre are—above all— observed
on cardiovascular diseases.
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According to the IOM recommendations,1,13 functional fiber should be measured prior to addition to the
food. This would avoid the problems of double counting
certain fibers if they or a derivative already occur in the
food; examples are pectins, inulin, fructooligosaccharides, and beta-glucans.1,13 However, workshop participants indicated that, for compliance purposes, testing of
foods after the addition of functional fiber is necessary.
With current methods, it is not possible to assess dietary
fiber and functional fiber in the final sample if the fiber
added is already present in its intrinsic and intact form in
the food. Since the IOM was not charged with determining new analytical methods, a collaborative effort will
have to occur among industry, academic, and governmental laboratories to modify or combine current methods and, where necessary and feasible, develop new ones
to accurately measure dietary and functional fiber in
finished food products.
Physiological Effects
Dietary fiber is clearly recognized to play an important role in a healthy diet. The benefits of dietary fiber are
not disputed, and by definition all dietary fibers are
presumed to have a physiological effect. However, the
specific nature of the beneficial physiological effect is
not designated in the IOM definition.1,13 According to
the IOM, specific physiological effects were not identified as part of the definition because new beneficial
effects are likely to be discovered.
In contrast, based on the IOM definition, physiological effects must be shown for functional fiber. Specific
measurable physiological effects of fiber that could be
used to establish functionality must be designated. Participants at the workshop noted that, given the lack of
acceptable physiological criteria for characterizing dietary fibers, establishing such criteria for classification of
functional fibers might be difficult.
To measure fiber, particularly functional fiber, by
the IOM definitions will require new approaches. First,
some criteria for functionality need to be established. For
example, if fermentability and viscosity are to be accepted criteria for functionality, as suggested in the IOM
reports,1,13 then in vitro tests need to be developed that
closely mimic the in vivo situation. Methods already
exist for batch fermentability and chemical viscosity that
could be modified and defined with clear protocols to
establish functionality. In choosing clinical tests of functionality, such as reduction of serum lipids, improved
laxation, and modulation of blood glucose, reference
standards should be developed and a meaningful degree
of change relative to the effects of a standard material
needs to be decided, similar to the Canadian regulation
surrounding laxation as an accepted physiological effect
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There are two general classes of methods that capture multiple substances as part of a total fiber determination: enzymatic-gravimetric methods (AOAC Methods
985.29 and 991.43) and enzymatic-chemical methods
(AOAC Method 994.13).9 The initial procedures to remove fat and/or sugar from the sample are similar,
including enzymatic digestion to remove starch and protein, dilute alcohol precipitation of soluble components,
and isolate residues by centrifugation. However, in enzymatic-chemical methods, the resulting residue is further treated and fractions assayed for identification of
neutral sugars as monosaccharides, uronic acids, and
Klason lignin by mass spectrophotometry, gas chromatography, colorimetry, or high-performance liquid chromatography. Enzymatic-chemical methods are tedious
and more costly than enzymatic-gravimetric methods,
and also require special skills. Additionally, the extra
effort to perform the enzymatic-chemical procedures
does not guarantee the elimination of tannins and Maillard reaction products from the total fiber determination
(although it does reduce the content of these compounds
compared with enzymatic-gravimetric methods).
Workshop participants agreed that more research is
needed to modify current methods and to develop new
methods to adequately account for all substances that
qualify as dietary fiber and functional fiber under the
IOM definition. As with all methods, newly developed
procedures should have safeguards to avoid double
counting when methods are combined and careful steps
in sample preparation to capture all needed constituents
and eliminate all substances that could be confounders.
Questions were raised as to whether the IOM definition of dietary fiber includes the specific oligosaccharides fructan and polydextrose, which are quantitated
using separate, specific procedures (AOAC Methods
985.29 and 991.43, respectively).13 According to the
IOM reports,1,13 low-molecular-weight fructans (such as
those found in Jerusalem artichoke and onions) would be
included as dietary fiber as long as they are intrinsic and
intact. Likewise, according to the IOM,1,13 isolates of
low-molecular-weight fructans would be included as
functional fiber because they have been shown to have
physiological health benefits. Analytical values for dietary, functional, and total fiber must include all polysaccharides, resistant starch, oligosaccharides, and lignin. This makes analysis more complicated, but
approved methods exist to measure each of these specific
non-digestible carbohydrate materials individually, so
full analysis is possible. For example, to measure polydextrose in the analysis of total dietary fiber, one could
analyze the sample with AOAC Method 985.29, collect
the filtrate from precipitated fiber, analyze for polydextrose by AOAC Method 2000.11, and add the two quantities.9
Regulatory Issues
The IOM definition of fiber has created a number of
concerns about the impact on regulations. The impact of
the division of fiber into dietary and functional fiber is a
major issue. There are also concerns about what criteria
need to be met to qualify as a functional fiber. If a
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material meets the criteria to be a functional fiber, will it
automatically qualify for a structure-function claim?
As discussed above, it may be necessary to put
regulations in place that prescribe specific methods for
quantifying functional and dietary fiber and for assessing
functionality in terms of beneficial physiological effects
in humans. The Canadian system for distinguishing novel-functional fiber from intact dietary fiber was discussed
in depth at the workshop, because it may be used as a
model for implementing the IOM definition. Studying
the Canadian program may also help in determining the
potential impacts of the IOM definition, if adopted by the
FDA, on regulations in the United States. However, it
should be pointed out that when a “novel fiber” in
Canada meets functional criteria, it becomes listed as
dietary fiber with no differentiation from other dietary
fibers.
Within the Canadian system, non-native fibers are
from traditional foods but do not occur naturally in the
foods to which they have been added (e.g., oat bran
added to a wheat starch pudding). Novel fibers are those
that have not traditionally been part of the human diet
(e.g., xanthan gum). The Canadian definitions of fiber are
as follows:
A “novel fiber” or “novel fiber source” means
a food that is manufactured to be a source of
dietary fiber and a) that has not traditionally
been used for human consumption to any significant extent or b) that has been chemically
processed, e.g. oxidized, or physically processed, e.g. very finely ground, so as to modify
the properties of the fiber contained therein, or
c) that has been highly concentrated from its
plant source).17
In Canada, to include a “novel fiber” as a “dietary
fiber,” it must meet the definition of a novel fiber (see
above), measure as dietary fiber by an accepted method,
and have proven physiological function.15,16 The regulations specify methods that can be used to measure dietary
fiber and describe criteria for studies assessing physiological effects (functionality). To be considered a valid
study, effects should be assessed in a clinical trial that
reports the type and number of subjects; the experimental
and control diets should be defined; and the outcomes of
the study should be compared with a reference material
and a positive control. With respect to laxation as an
accepted physiological effect of dietary fiber, the test
fiber must show 50% of the effect of the standard
positive control, wheat bran. Thus, the regulations in
Canada prescribe (for some physiological effects) the
criteria, tests, and standards to assess fiber analytically
and functionally. However, the Canadian system may be
considered to have overly stringent requirements for a
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of dietary fiber.16 Additionally, it is possible that new
biomarkers of fiber functionality will be included as their
importance in health promotion is accepted. Further,
less-invasive procedures or novel animal or in vitro
models for assessing bowel function could be developed
and added to the list of protocols to evaluate the functionality of fiber.
Also at issue is whether functional and dietary fiber
have significantly different beneficial physiological effects that require the establishment of a distinction between them. “Beneficial physiological effects” are a
requirement for functional fiber in the IOM definition but
not for dietary fiber. Even a material isolated from a
native plant source classified as dietary fiber must be
shown to have a physiological effect. In discussing this
point, the IOM fiber panel report13 states that studies
designed to investigate the physiological effects of dietary fiber (or dietary fiber compared with functional
fiber) are often complicated by the inability to separate
the effects of the dietary fiber from the associated nutrients. However, it was noted that many of the beneficial
physiological effects of fiber, both in human and animal
studies, were determined using isolated (and, by IOM
definition, functional) fibers.
In Canada, specific physiological benefits have been
included in the criteria to qualify non-native or novel
fibers for addition to foods.15,16,17 Criteria have been
established for three recognized physiological effects:
regularizing colonic function, normalizing serum lipids,
and attenuating the postprandial rise in blood glucose. A
fourth, weight control/suppressing appetite, was reviewed for inclusion in Canada’s regulation, but studies
have not yielded reliable, reproducible results. Therefore,
weight control is not yet considered an acceptable criterion to establish functionality. However, it is foreseeable
that in the future, weight control or other health benefits
attributed to the consumption of dietary or functional
fiber could make the list of criteria to establish functionality.
The IOM reports1,13 state that acceptable physiological effects must be identified and criteria established if
the definition is implemented. Standard protocols would
be needed to determine functionality. Questions were
raised in the workshop as to how this process would be
accomplished and what level of significance would be
required.
Consumer Issues
The possible impact on consumer attitudes and behaviors that could result from changing the IOM fiber
definition and fiber-related labeling regulations was also
addressed. Consumers are confused about fiber. According to several studies discussed at the workshop, less
than 50% of individuals in the United States with diabetes correctly identified foods with fiber; in a study in the
United Kingdom, approximately 50% of subjects listed
meat as a source of fiber.18 However, 60% of 1000 adults
surveyed said they are trying to choose a diet with
adequate fiber and look for it on the label at least some
of the time.19 In a recent consumer survey, 85% of
consumers polled indicated that they were concerned
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about the nutritional content of the foods they eat, yet in
an unaided question, none mentioned fiber as an item of
concern. Whole grains and fiber were mentioned by 10%
of consumers as something eaten to ensure a healthy diet.
When prompted, only 0.5% of consumers indicated that
they were concerned about fiber. Additionally, fiber
ranks 9th on consumers’ lists for label items considered
when purchasing foods. For the typical consumer, fiber is
not high on the list of concerns compared with calories,
fats, and sodium when making food choices.
Therefore, there is a gap in consumer behavior and
consumer knowledge with respect to dietary fiber. If the
IOM recommendations are implemented, the nutrition
facts panel could include a line for total, dietary, and
functional fiber. It is possible this could increase consumer awareness and interest in fiber and possibly increase the consumption of fiber. This would be a desirable outcome, because currently Americans consume,
on average, 15 g/d fiber and this amount appears to be
decreasing instead of increasing to meet the IOM
recommendations of 14 g/1000 kcals (approximately
28 g/d)1.
Unfortunately, the label change would be more
likely to confuse consumers. Consumers think current
food labels are already too complicated and want simpler
ones.20,21 If dietary fiber and functional fiber are separate
label entities, functional fiber could potentially be perceived as superior to dietary fiber. This could have two
possible impacts. It could increase functional and/or total
fiber intakes in the diet because consumers might specifically select products labeled as containing functional
fiber. The demand by consumers for foods with functional fiber could promote the development of new fiberenhanced products. Alternatively, increased demand for
products with added functional fiber and few other nutritional advantages could decrease the quality of the
diet, especially if consumers reduce their selection of
sources of dietary fiber in the form of fruits, vegetables,
and whole grains. This could lead to a net decrease in
total fiber intake or a reduction in the overall quality of
the diet.
Many participants in the workshop favored the use
of the functional-dietary fiber distinction as an internal
regulatory nomenclature, but with the information not
placed on the label. This would harmonize with current
Canadian regulations. Practically, the ultimate physiological impact of dietary and functional fiber should be
identical, and in most cases one would be unable to
analytically distinguish the effects of one from another in
a final food product. The message sent to consumers and
manufacturers by changing the nutrition content label
should be further investigated by focus groups and other
studies.
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material to be classified as a novel fiber, since only four
substances (ground, bleached oat hulls, soy cotyledon,
sugar beet fiber, and psyllium seed husk) have been
granted novel fiber status since 1985.
Canadian regulations also require that, in addition to
providing beneficial physiological effects, the safety of
novel fiber sources must also be established before they
may be used as ingredients in foods. If safe, they may be
used in foods, but cannot be claimed as a source of
dietary fiber unless they have been shown to have physiological efficacy. If efficacy has not been shown, they
are classified as an unproven novel fiber.
Approved novel fibers are included in the total fiber
declaration on the Canadian nutrition facts panel; the
Canadian food label does not distinguish between intact
and added fibers. There are three reasons that the Canadian model of declaring only total fiber on the label may
be useful in the United States. First, the beneficial physiological effects of a novel fiber that has been accepted as
a functional fiber compared with dietary fiber are the
same. Second, it keeps the number of terms on the label
from increasing, which could confuse consumers. Third,
there would no longer be a need for new methods to
distinguish dietary from functional fiber for label compliance purposes.
Confusion could also result in the area of fiber health
claims. If a material meets the criteria to be called
functional fiber, will it automatically qualify for a health
claim? Is there a system in place within the FDA for
processing and sorting through new claim submissions?
The IOM did not make recommendations for a new fiber
claim process using the new definition. Further adding to
potential confusion are the existing health claims that
refer to soluble and insoluble fiber. The IOM report
suggests that these terms should no longer be used. Thus,
the health claims regulations with regard to these terms
will need to be updated.
ACKNOWLEDGEMENTS
The IOM definitions of dietary fiber and functional
fiber impact analytical chemistry, clinical research, product development, labeling regulations, and ultimately
consumer health. However, there are areas where gaps in
knowledge and understanding still exist. These are summarized as a series of questions listed below.
● Who should decide which analytical or functionality
tests are acceptable?
● Who should identify acceptable physiological effects and criteria?
● Should analytical methods for quantitation and functionality be included in a regulation?
● Should the AOAC/Codex model for acquiring new
methods be used when setting methods for testing
physiological criteria?
● Are there true functional differences between dietary fiber and functional fiber in isolation?
● Are dietary fiber and functional fiber physiologically
different when they are in foods? Are there enough
data to support a distinction between the two?
● Can there be differentiation by analysis of dietary
fiber and functional fiber?
● Are there substances that are considered to be dietary fiber by current AOAC methods but that do not
have any physiological function?
● What criteria need to be met currently to qualify as
a functional fiber?
● What level of science will be required for “new”
physiological effects?
● What physiological functions should be considered,
and at what level, for a food ingredient to qualify as
a functional fiber?
● If a material meets the criteria to be a functional
fiber, will it automatically qualify for a structurefunction claim?
● Does the infrastructure exist to rigorously evaluate
the science supporting a functional fiber claim?
● How can the current fiber categories of soluble and
insoluble be integrated into the proposed definitions?
● How will implementation of the IOM definition
impact innovation?
● What will constitute approval of functional fibers?
This work was supported by a grant from the Technical Committee on Carbohydrates of the North American Branch of the International Life Sciences Institute
(ILSI NA). (For more information about the Committee
or ILSI NA, call 202-659-0074 or E-mail ilsina
@ilsi.org.) The opinions expressed herein are those of
the authors and do not necessarily represent the views of
ILSI NA. The authors would like to thank the members
of the Technical Committee on Carbohydrates and its
Fiber Working Group for their support of this workshop
and publication. We also thank the speakers for their
review of the manuscript to ensure the accuracy of the
information presented. The Committee appreciates the
stimulating presentations by the speakers, the interactive
participation of the guests, and the assistance of Richard
Carson, Senior Project Manager, and the staff of ILSI
NA, ILSI Europe, and ILSI, who contributed to the
successful workshop.
CONCLUSIONS
Changing the definition of dietary fiber in the United
States and possibly Canada has far-reaching analytical,
regulatory, industry, and consumer impacts, and the full
effects and understanding of these changes need to be
carefully addressed. Consideration must be given to existing dietary fiber definitions to harmonize with other countries, particularly trading partners, and to ensure that the
resulting regulations can be implemented and enforced.
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Workshop Speakers and Panelists
Ms. Sue Borra, International Food Information Council
Dr. Steve Brooks, Nutrition Research Division, Health
Canada
Dr. Ian Brown, the National Starch and Chemical
Company
Dr. Brenda Derby, Center for Food Safety & Applied
Nutrition (CFSAN), FDA
Dr. Jon DeVries, General Mills
Dr. Kathy Ellwood, CFSAN, FDA
Dr. Julie Jones, College of St. Catherine
Dr. Betty W. Li, US Department of Agriculture (USDA)
(Ret.)
Dr. David Lineback, Joint Institute for Food Safety &
Applied Nutrition, (JIFSAN), University of Maryland
Dr. Joanne Lupton, Texas A&M University
Dr. Jeanne Rader, CFSAN, FDA
Dr. Joanne Slavin, University of Minnesota
Dr. Alison Stephen, Heart & Stroke Foundation of
Canada
Dr. Paula Trumbo, CFSAN, FDA
Dr. Allison Yates, formerly IOM, National Academies of
Sciences, currently with ENVIRON
ILSI North America Statement of Purpose: The
North American branch of the International Life Sciences Institute (ILSI NA) is a public, non-profit scientific
foundation. ILSI NA advances the understanding and
application of scientific issues related to the nutritional
quality and safety of the food supply as well as health
issues related to consumer self-care products. The organization carries out its mission by sponsoring relevant
research programs, professional education programs and
workshops, seminars, and publications, as well as providing a neutral forum for government, academic, and
37
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KNOWLEDGE GAPS IDENTIFIED
industry scientists to discuss and resolve scientific issues
of common concern for the well-being of the general
public. ILSI NA also strives to foster the career development of outstanding new scientists. ILSI NA’s programs are supported primarily by its industry membership.
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